acepi - I had one of those Spanish Eibar .32 ACP something or another semi auto pistols many years ago. Jim K is right -(make sure the weapon is clear and the mag is out) pull the slide to the rear about an inch or so and twist the barrel. I can't remember clockwise or counter-clockwise about a quarter turn.
When you ease the slide forward, the barrel should come off (forward) with it. If I had it in my hands I could do it for you in a matter of seconds, but I'm doing this with a memory of a pistol I had over 45 years ago. As I remember, there are lugs on the barrel that lock the barrel onto the frame. To re-assemble, just reverse this process. Turn the pistol frame upside down, ease the barrel and slide onto the rails on the frame and gently pull the slide to the rear to compress the mainspring. Rotate the barrel so the locking lugs engage the lug recesses on the frame, and then ease the slide forward.
If this doesn't work, please forgive me as this is the best my memory can do at the moment. A competant (maybe an older guy) gunsmith can show you how to do this in just a couple of minutes. Good luck - Jim